[Federal Register Volume 68, Number 86 (Monday, May 5, 2003)]
[Proposed Rules]
[Pages 23666-23673]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-10268]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 146

[FRL-7488-7]


Underground Injection Control Program--Revision of Underground 
Injection Control Requirements for Class I Municipal Wells in Florida; 
Notice of Data Availability

AGENCY: Environmental Protection Agency.

ACTION: Notice of data availability.

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SUMMARY: On July 7, 2000, the Environmental Protection Agency (EPA) 
proposed revisions to the Underground Injection Control (UIC) 
regulations that would allow for continued wastewater injection by 
existing Class I municipal wells that have caused or may cause the 
movement of fluid into or between underground sources of drinking water 
(USDWs) in specific areas of South Florida. The revisions would provide 
owners and operators of such wells with an alternative for compliance 
with the existing UIC regulations, which prohibit such fluid movement, 
by allowing them to continue using their wells provided the injection 
does not endanger USDWs. Also in 2000, in a separate but related 
initiative, Congress directed EPA to conduct a relative risk assessment 
of four management options for treated municipal wastewater in South 
Florida: deep (Class I municipal) well injection, ocean disposal, 
surface discharge, and aquifer recharge. A separate document in today's 
Federal Register announces the availability and summarizes the findings 
of this relative risk assessment required by Congress. In this notice 
of data availability, EPA solicits public comment on how information on 
deep (Class I municipal) well injection in the relative risk assessment 
should inform the Agency's action on the July 7, 2000, proposed rule.

DATES: Comments on this notice of data availability must be in writing 
and either postmarked or received by the docket by July 7, 2003.

ADDRESSES: Send written comments to: Nancy H. Marsh, U.S. Environmental 
Protection Agency, Region 4, 61 Forsyth Street, SW., Atlanta, GA 30303-
8960. Comments may be submitted

[[Page 23667]]

electronically to [email protected]. For additional information see 
Additional Docket Information in the SUPPLEMENTARY INFORMATION section 
of this Federal Register document.

FOR FURTHER INFORMATION CONTACT: For inquiries, contact Nancy H. Marsh, 
Ground Water & UIC Section, U.S. Environmental Protection Agency, 
Region 4, 61 Forsyth Street, SW., Atlanta, GA 30303-8960 (phone: 404-
562-9450; E-mail: [email protected]) or Howard Beard, Office of 
Ground Water and Drinking Water, U.S. Environmental Protection Agency, 
EPA East, 1200 Pennsylvania Ave., NW., Mail Code 4606M, Washington, DC, 
20460 (phone: 202-564-3874; E-mail: [email protected]) or contact 
the Safe Drinking Water Hotline, phone 800-426-4791. The Safe Drinking 
Water Hotline is open Monday through Friday, excluding Federal 
holidays, from 9 a.m. to 5:30 p.m. eastern daylight-saving time.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. General Information
    A. Who are Regulated Entities?
    B. Additional Docket Information
    C. Will There Be Public Meetings?
II. Background
    A. Definition of Class I Municipal Wells
    B. Proposed Rule for Class I Municipal Wells in Florida
    C. Relative Risk Assessment of Management Options for Treated 
Municipal Wastewater in South Florida
III. Findings of the Relative Risk Assessment Pertaining to Deep 
Well Injection
    A. What Level of Treatment and Disinfection is Provided for Deep 
Well Injection?
    B. What Stressors Remain (After Treatment) That May Be a Concern 
for Deep Well Injection?
    C. What Exposure Pathways Are (Or May Be) of Significance for 
Deep Well Injection?
    D. What is the Overall Estimate of Risk for Deep Well Injection?
    E. What Are the Important Data or Knowledge Gaps for Deep Well 
Injection?
IV. Relevance of These Findings for the Final Rule for Class I 
Municipal Wells in South Florida
    A. Additional Wastewater Treatment Prior to Injection
    B. Feasibility of a Hydrogeologic Demonstration
    C. Some Deep Wells May Have Been Misclassified as Class I, When 
They Are Actually Class V
V. Solicitation of Comment

I. General Information

A. Who Are Regulated Entities?

    This notice is limited in application to the owners and/or 
operators of existing deep (Class I) underground injection wells that 
inject domestic wastewater effluent in specific counties in Florida. 
The counties are: Brevard, Broward, Charlotte, Collier, Dade, Flagler, 
Glades, Hendry, Highlands, Hillsborough, Indian River, Lee, Manatee, 
Martin, Monroe, Okeechobee, Orange, Osceola, Palm Beach, Pinellas, St. 
Johns, St. Lucie, Sarasota, and Volusia. Regulated categories and 
entities include:

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                Category                       Examples of entities
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Municipalities and Local Government....  Class I municipal injection
                                          wells disposing of domestic
                                          wastewater effluent in certain
                                          parts of Florida.
Private................................  Class I municipal injection
                                          wells disposing of domestic
                                          wastewater effluent in certain
                                          parts of Florida.
------------------------------------------------------------------------

    This table is not intended to be exhaustive, but rather provides a 
guide for readers regarding entities likely to be regulated by this 
action. This table lists the types of entities that EPA is now aware 
could potentially be regulated by this action. Other types of entities 
not listed in the table could also be regulated by this action. To 
determine whether your injection well might be regulated, you should 
carefully examine the applicability criteria in 40 CFR 146.15 of the 
July 7, 2000, proposed revisions to the Class I UIC regulations (65 FR 
42234). If you have questions regarding the applicability of this 
action to a particular entity, consult one of the persons listed in the 
preceding FOR FURTHER INFORMATION CONTACT section.

B. Additional Docket Information

    When submitting written comments (see ADDRESSES section) please 
submit an original and three copies of your comments and enclosures 
(including any references). The record is available for inspection from 
8 a.m. to 3:30 p.m. Eastern daylight-saving time, Monday through 
Friday, excluding legal holidays, at the Environmental Protection 
Agency, Region 4 Library (9th Floor), Sam Nunn Atlanta Federal Center, 
61 Forsyth St., SW., Atlanta, GA 30303-8960. For information on how to 
access Docket materials, please call 404-562-8190 and refer to the 
Florida UIC docket.

C. Will There Be Public Meetings?

    EPA plans to have public meetings in Florida during the comment 
period. EPA will announce the dates, times and locations of those 
public meetings in a subsequent Federal Register document.

II. Background

A. Definition of Class I Municipal Wells

    Class I injection wells are wells that inject fluids beneath the 
lowermost formation containing, within one-quarter mile of a well bore, 
a USDW (40 CFR 144.6(a)). Class I wells can be used to inject 
hazardous, industrial, or municipal wastes. Class I municipal wells 
inject treated wastewater from publicly or privately owned and operated 
facilities that treat domestic wastewater, which is principally derived 
from dwellings, business buildings, and institutions. Domestic 
wastewater is commonly referred to as sanitary wastewater or sewage. 
Treated wastewater from industrial facilities, often controlled through 
pretreatment standards, may also be found in this wastewater. 
Currently, Class I municipal wells are located only in the State of 
Florida.

B. Proposed Rule for Class I Municipal Wells in Florida

    EPA has established minimum requirements for Class I municipal 
wells and other underground injection activities through a series of 
UIC regulations at 40 CFR parts 144 through 147, developed under the 
authority of the Safe Drinking Water Act (SDWA). These regulations 
ensure that Class I municipal wells will not endanger USDWs by 
prohibiting the movement of any contaminant into USDWs.
    On July 7, 2000, EPA proposed revisions to the UIC regulations that 
would allow continued wastewater injection by existing Class I 
municipal wells that have caused or may cause movement of contaminants 
into USDWs in specific areas of Florida (65 FR 42234). Continued 
injection would be allowed only if owners or operators meet certain 
additional requirements that provide adequate protection for USDWs. If 
new requirements are not promulgated, owners and/or operators of wells 
affected by the proposal would

[[Page 23668]]

be required to close their wells and adopt different wastewater 
disposal practices, which could consist of surface water disposal, 
ocean outfall, and/or reuse. Use of these alternative disposal 
practices would likely require the construction of facilities with 
advanced wastewater treatment, nutrient removal, and high-level 
disinfection.
    EPA proposed two primary options for the additional requirements: 
Option 1--Facilities must provide advanced wastewater treatment and 
high-level disinfection with a demonstration that the injectate will 
not cause a USDW to exceed any national primary drinking water 
regulations in 40 CFR part 141 and other health-based standards (e.g., 
Federal or State health advisories approved by the UIC Program 
Director, if a national primary drinking water regulation is not 
available for specific pollutants); and Option 2--Facilities must 
conduct an in-depth hydrogeologic demonstration that the injection 
operation would not cause fluids that will migrate into the USDW to 
exceed any national primary drinking water regulations in 40 CFR part 
141 and other health-based standards and, if the demonstration is not 
successful, must provide advanced treatment, as necessary, to ensure 
that injectate will not cause a USDW to exceed any national primary 
drinking water regulations in 40 CFR part 141 and other health-based 
standards. This second option also proposed a provision whereby all 
facilities qualifying for authorization to inject under this option 
would be required to install advanced wastewater treatment and high-
level disinfection by 2015. The preamble to the proposal describes in 
detail the history of domestic wastewater injection in Florida, along 
with the features of Florida geology that have allowed some of that 
injected wastewater to enter USDWs. EPA received approximately 1,200 
comments on the proposal (the comment period closed on October 22, 
2000). The Agency will address these comments, along with comments 
received in response to this notice of data availability, as part of 
the final action on this rulemaking.

C. Relative Risk Assessment of Management Options for Treated Municipal 
Wastewater in South Florida

    As part of EPA's fiscal year 2000 appropriations bill, Congress 
included the following provision: ``Within available funds, the 
conferees direct EPA to conduct a relative risk assessment of deep well 
injection, ocean disposal, surface discharge, and aquifer recharge of 
treated effluent in South Florida, in close cooperation with the 
Florida Department of Environmental Protection and South Florida 
municipal water utilities.'' Because this directive came at a time when 
EPA's work on the July 7, 2000, proposal was substantially complete, 
the Agency decided to proceed with the proposal and the relative risk 
assessment along separate but converging paths. First, EPA published 
and sought comment on the proposal based on information available at 
that time. Second, EPA initiated and conducted the relative risk 
assessment with the intent of using relevant findings to inform the 
final rulemaking.
    EPA started the relative risk assessment by working with 
stakeholders to develop an appropriate methodology. The Agency first 
outlined a proposed methodology following standard risk assessment 
principles and guidance, such as the ``Guide for Developing Conceptual 
Models for Ecological Risk Assessments.'' \1\ EPA then held a 
stakeholders meeting on March 20, 2001, in Tallahassee, Florida to 
discuss the proposed methodology. The meeting was attended by 17 
stakeholders representing municipal water utilities, regulators, and 
community and environmental groups. Participants offered comments on 
the proposed methodology, which EPA adopted accordingly.
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    \1\ Prepared by G.W. Suter II of Oak Ridge National Laboratory 
for the U.S. Department of Energy. Report No. ES/ER/TM-186 issued in 
May 1996. Available at http://www.esd.ornl.gov/programs/ecorisk/tm186.pdf.
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    The methodology involved a process for investigating the four very 
different wastewater disposal options: deep well injection, aquifer 
recharge, discharge to ocean outfalls, and discharge to other (non-
ocean) surface water bodies. Each option has its own specific stressors 
(hazards), exposure pathways, receptors, and effects. Parameters that 
are relevant to one particular disposal option are not necessarily 
relevant to the remaining three. Therefore, a strictly quantitative 
comparison between the four options was not possible.
    Instead, EPA conducted what is termed a relative risk assessment to 
both assess the risks and allow comparisons. Individual risk 
assessments were completed for each wastewater disposal option and the 
risks associated with each were characterized. The risks and risk 
factors identified through each option-specific disposal option were 
then evaluated and described. The overall comparisons and conclusions 
were then presented as relative risk assessment matrices.
    The steps involved in the relative risk assessment included 
developing a Generic Risk Analysis Framework followed by conducting 
analyses of option-specific conceptual models. Data from many sources 
were used to support the analyses. These sources include the Florida 
Department of Environmental Protection, utilities (and the South 
Florida Water Environment Utility Council), and municipalities in South 
Florida. EPA also worked with a panel of experts both inside and 
outside of EPA and from a variety of fields to review and incorporate 
data and information acquired through exhaustive searches of the 
relevant scientific research literature. Risk characterization for each 
option included identifying and describing the associated risks, their 
potential magnitude, and the potential effects on human and ecological 
health. The relative risk assessment then described and compared risks 
for all four wastewater management options. Finally, the relative risk 
assessment was peer reviewed in accordance with the Agency's Peer 
Review Handbook.

III. Findings of the Relative Risk Assessment Pertaining to Deep Well 
Injection

    The relative risk assessment offers comparisons of deep well 
injection, ocean disposal, surface discharge, and aquifer recharge of 
treated municipal wastewater in South Florida. Findings related to each 
of these management options are highlighted in a separate notice in 
today's Federal Register and presented in greater detail in the 
relative risk assessment report. EPA is seeking comment in sections IV 
and V below on how these findings should inform the final rulemaking on 
Class I municipal wells in Florida. To provide background and context 
for those following sections, the remainder of this section summarizes 
how the relative risk assessment addresses five key questions 
specifically related to deep well injection.

A. What Level of Treatment and Disinfection Is Provided for Deep Well 
Injection?

    All facilities that manage municipal wastewater by deep well 
injection in Florida are required to provide, at a minimum, secondary 
treatment of the wastewater prior to injection. Secondary treatment 
comprises biological removal of dissolved organic and inorganic matter, 
commonly through such methods as activated sludge and trickling filter 
processes. By itself, secondary treatment does not remove 
microorganisms by either disinfection (through the addition of 
chlorine, for example) or filtration.

[[Page 23669]]

    Utilities that employ deep well injection in South Florida must 
maintain disinfection capability, but many do not disinfect treated 
effluent prior to injection. For example, treatment of wastewater that 
is injected by Class I municipal wells in Dade and Brevard Counties 
consists of secondary treatment with no disinfection, although backup 
disinfection capability is required. In contrast, in Pinellas County, 
wastewater is treated to reclaimed water standards before being 
discharged into Class I municipal wells, because the Class I wells are 
used to dispose of reclaimed water during periods of wet weather. 
Reclaimed water standards, as specified by the State of Florida, 
include secondary treatment and a variety of techniques to address 
pathogenic microorganisms, including filtration and high-level 
disinfection.

B. What Stressors Remain (After Treatment) That May Be a Concern for 
Deep Well Injection?

    ``Stressors'' include chemical or biological agents that may cause 
adverse effects if exposure levels are high enough. They may pose a 
risk to human health and/or ecological health if they reach receptors 
(USDWs, drinking water supply wells, surface waters) at sufficiently 
high concentration levels. EPA has included USDW's as a receptor 
because of the Agency's responsibility under the Safe Drinking Water 
Act to prescribe regulations for State underground injection programs, 
like Florida's, that contain minimum requirements to prevent 
underground injection from endangering USDW's.
    In cases where injectate has received secondary treatment only, 
bacteria, viruses, and protozoa (e.g., Cryptosporidium and Giardia) are 
generally not inactivated prior to deep well injection in South 
Florida. In cases, such as Pinellas County, where injectate has been 
treated to reclaimed water standards, viruses and bacteria have likely 
been largely inactivated through disinfection and protozoa have been 
largely removed through filtration.
    Disinfection (or chlorination) by-products such as trihalomethanes 
may also be present in some wastewater, although no data are available 
to suggest that such by-products are a serious concern for deep well 
injection or any of the other wastewater management options studied in 
South Florida. EPA would not expect such by-products to be present in 
wastewaters that have not undergone basic disinfection, as is often the 
case for Class I injectate.
    Nutrients are potential ecological stressors for deep well 
injection, assuming the injected wastewater contains significant 
quantities of nutrients and assuming the injected wastewater is able to 
migrate underground and discharge into the ocean or into other surface 
water bodies. Nutrients can potentially stimulate production of algae, 
which can lead to adverse side effects such as eutrophication. Nitrogen 
is the primary nutrient concern for Class I injection, because of its 
mobility in ground water. Nitrogen is also the primary nutrient of 
concern if it migrates to the ocean, because it is generally the 
limiting nutrient for algae production in the ocean. Phosphorus is of 
less concern for underground injection because it tends to adsorb 
quickly to sediment or soil.

C. What Exposure Pathways Are (or May Be) of Significance for Deep Well 
Injection?

    An ``exposure pathway'' is the course a stressor takes from a 
source of release to an exposed organism. It is defined by the 
different environmental media through which a stressor migrates (e.g., 
air, surface water, ground water) as well as the mechanism by which an 
organism is actually exposed (e.g., inhalation, drinking).
    There are documented impacts to USDWs resulting from deep well 
injection in South Florida, which raise concerns about potential human 
exposures via the drinking water pathway. Beginning in the late 1980s, 
ground water monitoring wells at 18 of the 45 municipal facilities that 
utilize Class I deep well injection in South Florida began to detect 
the movement of fluid outside of the permitted injection zones. 
Movement of effluent into USDWs either has been confirmed or is 
suspected at nine facilities, as evidenced by levels of nitrates and 
ammonia, as well as significant changes in dissolved solids 
concentrations.
    Contaminants released by deep well injection can migrate through 
the subsurface and discharge into marine and/or surface waters, where 
they could pose risk via other pathways if loadings were sufficiently 
large. Such subsurface transport is especially a concern where 
contaminants can migrate relatively rapidly and with relatively little 
attenuation through preferential flow paths (fractures, faults, and 
solution cavities) common in the carbonate rocks in South Florida. 
Potential concerns associated with injectate migrating into the ocean 
or other surface water bodies could include the risk of ecological 
damage as well as the risk of human exposure to contaminants through 
such recreational activities as fishing, swimming, and boating.

D. What Is the Overall Estimate of Risk for Deep Well Injection?

    The human health risks associated with deep well injection of 
treated municipal wastewater in South Florida are generally low. 
Several factors affect risk levels at particular sites.
    The degree of wastewater treatment, and in particular the level of 
disinfection and filtration of pathogenic microorganisms (e.g., 
Cryptosporidium, Giardia), is one such factor. Risks are lower when 
wastewater has been treated to remove microorganisms. For wastewater 
that has received only secondary treatment, risk would be high in 
situations where the injectate migrates through fractures, faults, and 
solution cavities and lower in situations where the injection is 
dominated by porous media flow, characterized by long travel times to 
current or potential drinking water sources, and flows through fine 
pore spaces capable of retaining microorganisms.
    Once Cryptosporidium, Giardia, and other stressors are released to 
the environment, the level of risk they pose to human health depends 
largely on how likely they are to enter drinking water supplies and 
over what time horizon. The record shows that such contamination of 
drinking water supplies or USDWs is a possibility as a result of the 
movement of fluid found at some injection facilities. In some cases, 
the time frames for fluid to potentially reach USDWs are short enough 
that treatment of injectate (i.e., inactivation, filtration) may be 
warranted.
    Overall, the risk to surface water ecosystems is low when treated 
wastewater is managed by deep well injection in South Florida. The 
potential for damage may be higher where treated wastewater is released 
in proximity to surface water that already has impaired water quality, 
which is the case for many surface water bodies in South Florida. In 
these cases, the nutrients that might enter impaired waters could 
exacerbate existing water quality and ecological problems. The dynamics 
of potential fluid movement from UIC wells to surface waters is still 
not well understood, however, at present there is no evidence of 
contamination of surface water by Class I injectate.
    Deep well injection could also pose a risk to marine ecology if 
contaminants readily migrate and discharge to offshore waters. However, 
whether this actually happens in South Florida, and whether it poses a 
real threat in the ocean, is unknown. Given, however, that direct 
discharge of effluent which has received only secondary treatment and 
basic disinfection to the ocean

[[Page 23670]]

appears to pose little risk due to rapid dilution, it is unlikely that 
seepage from ground water to the ocean would pose a significant risk.

E. What Are the Important Data Or Knowledge Gaps for Deep Well 
Injection?

    In conducting the relative risk assessment, EPA found that there is 
a lack of definitive studies in South Florida that use a physical or 
chemical tracer or indicator to show whether stressors detected in 
aquifers come from treated wastewater managed by deep well injection, 
and if so, by what likely contaminant transport pathways (porous versus 
conduit flow). In addition, without more definitive tracer studies, it 
is difficult to assess the potential effects of local geochemical 
conditions on the fate and transport of injected treated wastewater.
    While results from ground water monitoring around some Class I 
municipal wells in South Florida confirm that fluids have migrated out 
of the permitted injection zone, the full areal extent of USDW 
contamination is not known. This is not only because available 
monitoring data are limited, but also because the location and 
connectivity of natural conduits for fluid flow (fractures and solution 
cavities in the underground formations) are difficult to predict.
    The fate and transport of pathogens in South Florida's aquifers are 
not completely understood. For example, the rates of microbial 
survival, inactivation, and transport are difficult to predict. Also 
uncertain are the rates of microbial straining or filtration by 
geological materials under different fluid flow scenarios, including 
porous media and conduit flow. Even with the most sophisticated 
modeling, or with expensive monitoring, this information is difficult 
to verify since the formations are thousands of feet underground. There 
is also insufficient data at present on the presence and viability of 
pathogens in injectate that has migrated out of the injection zone. 
However, the presence of coliform bacteria in injectate that has 
migrated, a long accepted indicator of the presence of sewage, 
indicates the likely presence of pathogenic microorganisms.

IV. Relevance of These Findings for the Final Rule for Class I 
Municipal Wells in South Florida

    EPA requests comment on how the findings from the relative risk 
assessment, and identified data gaps, help inform the final regulatory 
action on the July 7, 2000, proposal. EPA specifically requests comment 
on the three issues discussed below.

A. Additional Wastewater Treatment Prior to Injection

    EPA believes the following findings from the relative risk 
assessment are relevant to the question of the extent to which 
additional treatment may be needed for Class I injectate that has a 
potential to reach USDWs.
    1. Wastewater that does not undergo disinfection contains viruses 
and pathogenic bacteria and protozoa that have not been inactivated. 
Although the fate and transport of these pathogens in South Florida's 
subsurface is not well known, monitoring and modeling data suggest 
that, at some sites, fluid may migrate at rates that are sufficient to 
transport active and infective pathogens into USDWs. For example, using 
first order analytical modeling with conservative parameters and 
assuming flow is dominated by bulk flow through preferential flow 
paths, travel times to the base of the USDW of 170 days, 14 years, and 
86 years have been estimated for Pinellas, Dade, and Brevard Counties 
respectively. There is significant uncertainty as to how long the 
viruses, protozoa, and bacteria will remain alive and to what extent 
they may affect existing and future sources of drinking water, although 
it is expected that significant attenuation and die-off would occur in 
the deep subsurface over long travel times. The limited data that are 
currently available show one-log (90%) inactivation rates in aquatic 
media ranging from 40 to 200 days for Cryptosporidium, 6 to 50 days for 
bacteria, and 1 to 30 days for viruses. This suggests that pathogen 
contamination would likely be a concern in areas where travel times are 
potentially short (e.g., Pinellas County). For such areas, additional 
treatment (e.g., primary treatment, coagulation, settling, filtration, 
and high-level disinfection) would likely be needed to inactivate, 
remove, or greatly reduce pathogens in order to increase the level of 
protection for current and future sources of drinking water. (As noted 
above, wastewater in Pinellas County is already treated to reclaimed 
water standards, which include both disinfection and filtration.) 
Additional treatment beyond secondary may also be appropriate to 
address pathogenic microorganisms in cases where injection of large 
volumes of wastewater increases the uncertainty regarding the areal 
extent of fluid movement and travel times for fluid to potentially 
reach USDWs.
    2. Insufficient confinement is evident at some facilities and 
locations. At nine facilities, there is either confirmed or suspected 
contamination of USDWs as a result of the movement of fluid from 
designated injection zones. This is a violation of Federal and State 
Class I UIC requirements, which prohibit any contaminants from entering 
USDWs. At nine other facilities, there is evidence of movement outside 
of the injection zone, though not yet into USDWs. Monitoring reports 
from some facilities suggest that fluid movement has resulted in 
fluctuations in total dissolved solids (TDS) concentrations and less 
pronounced changes in the concentrations of other potential stressors 
(e.g., fecal coliform, nitrate, ammonia, and total Kjeldahl nitrogen). 
Such fluid may have the potential to contaminate future sources of 
drinking water and place existing public and private water supplies at 
risk.
    3. The full areal extent of fluid movement is not known. Nearly 500 
million gallons per day (mgd) are disposed of through deep well 
injection at 42 sites in South Florida, with rates for individual wells 
ranging from less than 1 to more than 100 million gallons per day 
(mgd). While the dynamics of horizontal movement at any of these 42 
sites of this quantity of water are not well understood, there is some 
evidence that water with the potential to reach USDWs (due to 
inadequate confinement) may not travel far. The first-order analytical 
modeling results presented in the relative risk assessment show 
horizontal travel distances at the surface ranging from 0.1 to 1.6 
miles assuming rapid (bulk) vertical flow, and ranging from 1.2 to 16 
miles assuming slow (porous media) flow. Note that a travel distance of 
16 miles is modeled to occur only under a very long time horizon (1,188 
years). Two members of EPA's External Peer Review Panel expressed 
concern, however, regarding the feasibility of using numerical models 
to assess the pattern of flow in and around the discharge zone (known 
as the Boulder zone), and to account for several trillion gallons of 
treated municipal wastewater that has been injected into the Boulder 
zone since the inception of Florida's Class I UIC program. These Panel 
members also pointed out that the risk could be significantly higher to 
USDWs than the modeling calculations that assumed porous media flow 
suggest, due to large uncertainties that were not accounted for in this 
modeling. In response to these concerns, EPA developed a second model 
assuming bulk flow through preferential flow paths, with travel times 
for injectate to reach USDWs and drinking water wells that were an 
order

[[Page 23671]]

of magnitude shorter than the porous media flow model. EPA believes, 
and the reviewers agreed, that this second model largely addresses the 
concerns raised, but recognizes that significant uncertainty regarding 
the dynamics of underground fluid movement remain.
    4. The location and connectivity of natural conduits for flow 
(i.e., fractures, faults, and solution cavities) are unknown, although 
their existence is well known by the type of rock present (e.g., 
limestone) and confirmed by logs during deep well construction. Where 
such conduits are present, they may contribute to rapid migration of 
injected fluids or displaced formation water, with little attenuation 
of contaminant concentrations. Furthermore, such conduits may result in 
unpredictable patterns of movement in the subsurface. The relative risk 
assessment attempts to simulate such flows on a regional (not site-
specific) basis using a first order analytical model with conservative 
parameter assumptions. However, there is significant uncertainty in 
these results.

B. Feasibility of a Hydrogeologic Demonstration

    Option 2 proposed on July 7, 2000, (as described above) would allow 
facilities operating Class I municipal wells that have caused or may 
cause fluid movement in South Florida to continue injection if they 
perform a detailed hydrogeologic demonstration showing that injection 
will not cause fluids to migrate and cause USDWs to exceed any national 
primary drinking water regulations in 40 CFR part 141, and other 
health-based standards. Where this demonstration cannot be made, Option 
2 would require facilities to provide additional treatment as necessary 
to address contaminants of concern and ensure that the continued 
injection does not endanger USDWs. All facilities qualifying for 
authorization to inject in accordance with Option 2 would be required 
to have advanced wastewater treatment and high-level disinfection in 
place by the year 2015. This requirement to phase in additional 
treatment by 2015 was intended to provide municipalities with more time 
to provide additional treatment if the municipality could conduct a 
successful hydrogeologic demonstration.
    EPA believes the following relative risk assessment findings are 
relevant for assessing the feasibility of conducting a credible 
detailed hydrogeologic demonstration, as proposed under Option 2.
    1. As noted in the preceding section, the specific location, 
extent, and connectivity of natural conduits for flow are unknown and 
unpredictable in the South Florida areas targeted by the proposal. 
Therefore, some of the key parameter values that would be used in 
ground water modeling may be highly uncertain, and this may lead to a 
broad range of predicted results for the location and movement of the 
injected fluid. The relative risk assessment attempted to address this 
issue on a regional (not site specific) basis by using first order 
analytical methods to modeling bulk/preferential flow. This may or may 
not be practicable for site-specific numerical modeling.
    2. The ground water monitoring wells (or networks of monitoring 
wells) at most deep well facilities in South Florida are sufficient 
only for the purpose of providing an early warning of fluid movement. 
Typically, ground water monitoring networks are used at waste 
management facilities (e.g., hazardous waste landfills) to detect and 
characterize the movement of relatively small volumes of contaminants 
in shallow ground water. No deep well municipal waste disposal 
facilities in South Florida have designed, constructed, and implemented 
ground water monitoring programs capable of describing the full areal 
extent of fluid movement, especially where natural conduits for flow 
are present. In addition, few facilities perform extensive monitoring 
between the base of the lowermost USDWs and the shallower surficial 
aquifers. As noted above, however, modeling results suggest that the 
areal extent of contamination that reaches the surface rapidly through 
preferential flow may be limited (up to a few miles), although there is 
significant uncertainty in these results due to the volumes of fluid 
being injected and the possibility of fairly rapid horizontal movement 
in the Boulder zone below the USDW, which was not explicitly modeled.
    3. It is unclear whether it would be practicable to provide enough 
additional ground water monitoring wells to provide the information 
needed to demonstrate that fluid movement is not occurring and USDWs 
are not being contaminated at sites where natural conduits for flow 
exist. Because flow could well progress at different rates in different 
directions, monitoring results for well locations at such sites would 
not necessarily be representative of conditions at unmonitored 
locations. Furthermore, there could be concern about the installation 
of many monitoring wells to examine a particular site, because they may 
penetrate rock and other materials that are otherwise barriers to fluid 
movement. If such monitoring wells are constructed or managed 
improperly, they could present man-made conduits for fluid movement.

C. Some Deep Wells May Have Been Misclassified as Class I, When They 
Are Actually Class V

    Given the extent of fluid movement documented at some sites, as 
well as information concerning the geology and the construction of some 
municipal wells in South Florida, it is possible that some wells may 
have been misclassified as Class I when they are actually Class V. 
According to the Federal UIC regulations, Class I wells ``inject fluids 
beneath the lowermost formation containing, within one quarter mile of 
the well bore, an underground source of drinking water'' (40 CFR 
144.6(a)(2)). Class V wells are defined as wells that are not included 
in Class I, II, III, or IV. Typically, Class V wells release non-
hazardous fluids into or above formations containing USDWs.
    Separate from the issue of how Class I and Class V wells are 
defined, the Federal Class I and Class V UIC programs differ in their 
basic approach to protecting USDWs. The basic standard of protection in 
the Class I program is to ensure that there is no movement of any 
contaminant into USDWs. This standard is achieved through a Class I 
regulatory program that focuses on the development and enforcement of 
stringent permit requirements, including, but not limited to, criteria 
for well siting, construction, and operation and maintenance. A key 
component of the Class I program is ensuring that adequate confinement 
exists between the permitted injection zone and USDWs at a given site.
    Since most Class V wells release fluids either directly into or 
above USDWs, they by definition cause the movement of fluid, which may 
contain contaminants, into or above USDWs. Therefore, the basic 
standard of protection in the Class V program is to prevent any 
contaminants in the fluid from endangering USDWs. Protection efforts in 
the Class V program mainly focus on regulating and monitoring injectate 
quality to ensure that the movement of injected fluid will not contain 
any contaminants that may endanger USDWs. This standard is achieved 
through inventory and assessment requirements, additional reporting 
requirements, closure requirements, and other requirements (possibly 
including permitting requirements) believed by UIC program staff to be 
necessary to protect drinking water supplies.
    The failures of confinement that have been documented at some 
municipal

[[Page 23672]]

well sites in South Florida, which are most likely attributable to the 
presence of natural conduits for flow in the subsurface, suggest that 
the injection zones used by these municipal wells are not sufficiently 
separated from overlying USDWs by a confining layer to prevent fluid 
movement upward into the USDW. The injectate from these wells is, 
therefore, entering into a USDW. Injection zones in South Florida often 
share a ``degree of lithologic homogeneity'' (as specified in the 40 
CFR 144.3 definition of ``formation'') with the overlying ``confining 
layers'' and USDWs (i.e., each consists of carbonate sequences). In 
some locations, the injection zones, ``confining layers,'' and USDWs 
may be said to exist within one formation. It is possible that a well 
injecting at such a location may not be appropriately classified as a 
Class I well.
    Information collected for the relative risk assessment raises a 
question as to whether certain South Florida municipal disposal wells 
should have been classified as Class V at the time they were first 
permitted. In particular, all of the lithologic units of the upper 
Floridan Aquifer in Pinellas County and the lower Floridan Aquifer in 
Miami-Dade consist of limestone and dolomite that have shown evidence 
of solution cavities and fractures. These natural conduits for fluid 
flow raise a question as to whether lithologic units in these aquifers 
are effective confining layers and whether the injection zones and 
overlying USDWs are in different and distinct formations, as they were 
believed to be when the wells were originally sited, constructed, and 
permitted as Class I wells.

V. Solicitation of Comment

    In the July 7, 2000, proposed rule (65 FR 42234), EPA proposed 
regulatory options that would allow for continued wastewater injection 
by existing Class I municipal wells that have caused or may cause fluid 
movement in specific areas of Florida. The relative risk assessment 
described in this notice and in a companion notice appearing elsewhere 
in today's Federal Register contains some new information regarding the 
potential risks of deep well injection of municipal wastewater in South 
Florida. The Agency is soliciting comment on whether and how the 
findings of the relative risk assessment should inform the Agency in 
developing the final rule for wells currently classified as Class I 
deep municipal wells in South Florida.
    In addition to the issues discussed above, the Agency is soliciting 
comment on the following three issues:
    1. The Agency solicits comment on an alternative option for 
defining the appropriate level of wastewater treatment required for 
continued injection in deep municipal wells in South Florida. The 
proposed rule solicited comment on four levels of advanced wastewater 
treatment, nutrient removal, and high-level disinfection that, under 
Option 1 and by the year 2015 under Option 2, would be required of 
facilities operating wells that have caused or may cause fluid 
movement. The alternatives proposed under Option 1 were: (1) Treatment 
to 10-24 mg/l biochemical oxygen demand (BOD) with disinfection; (2) 
treatment to 10-24 mg/l BOD with disinfection and nutrient removal; (3) 
treatment to <10 mg/l BOD with disinfection; and (4) treatment to <10 
mg/l BOD with disinfection and nutrient removal. These levels were used 
by the 1996 Clean Water Needs Survey Manual to delineate and cost 
levels of advanced treatment. To achieve high-level disinfection, the 
proposal said owners and/or operators must allow the wastewater to 
remain in contact with at least 1.0 mg/l of free chlorine for at least 
15 minutes of contact with no fecal coliform.
    Several commenters suggested that the proposed standards for BOD 
removal are inappropriate for the protection of ground water for the 
purpose of protecting human health. These commenters stated that BOD 
levels are typically used for the protection of ecological values in 
surface water, not the protection of human health associated with 
drinking ground water. The commenters also pointed out that the main 
stressor of concern in the injectate is pathogens, not BOD. Separately, 
commenters noted that EPA's proposed definition of high-level 
disinfection differs from the State of Florida's definition of the same 
term in Rule 62-600.440, F.A.C., which commenters thought would result 
in confusion. Other commenters suggested that any new EPA wastewater 
treatment requirements should be consistent with corresponding state 
requirements. For example, Florida's regulations for waste treatment 
and disinfection applicable to reclaimed water that may come into human 
contact (Rule 62-610.460, F.A.C.) and ground water disposal by 
underground injection in Class V wells (Rule 62-600.540(2) and (Rule 
62-600.440(5), F.A.C.) are similar to the more advanced levels of 
treatment envisioned under Option 1 of the proposed rule that require 
filtration before disinfection. As stated in the Florida regulations, 
by removing TSS before disinfection, filtration serves to increase the 
ability of the disinfection process to inactivate viruses and other 
pathogens. Filtration also serves as the primary barrier for removal of 
protozoan pathogens (Cryptosporidium, Giardia, and others).
    Based on these comments, EPA is now considering and soliciting 
comments on prescribing wastewater treatment requirements in language 
that differs from the four alternatives proposed on July 7, 2000 but 
conforms with relevant state requirements. The Agency is not asking for 
additional comment on the four levels of advanced wastewater treatment, 
nutrient removal, and disinfection described in the proposal. Under 
this alternative, the Agency would simply adopt, in lieu of the four 
standards in the proposal, the Florida standards in Rule 62-610.460, 
F.A.C. (for waste treatment and disinfection applicable to reclaimed 
water that may come into contact with people) or the standards in Rule 
62-600.540(2) and Rule 62-600.440(5), F.A.C. (for ground water disposal 
by underground injection in Class V wells). Specifically, EPA would 
require advanced wastewater treatment that results in treated water 
meeting, at a minimum, secondary treatment and high-level disinfection 
as defined in the Florida regulations. Also, filtration would be 
required for TSS control prior to disinfection, which would specify 
that the treated wastewater not contain more than 5.0 mg/l of TSS 
before the application of the disinfectant. EPA believes that this 
treatment standard might offer some important advantages over the 
alternatives proposed before. In particular, it might better address 
the risks associated with pathogens, and it would be consistent with 
the standards already adopted and implemented in Florida for reclaimed 
water and wastewater disposed of through Class V injection wells, which 
are part of domestic wastewater treatment systems.
    The Agency asks commenters if this standard for advanced treatment 
and high-level disinfection should be specified in the final rule and 
requests that commenters describe the type of treatment that would be 
necessary to achieve the performance standards (i.e., national primary 
drinking water regulations and other health-based standards). Although 
the Agency believes that the design and construction costs of this 
option are equivalent to those for the earlier proposed treatment 
options that required treated effluent concentration of less than 10 
milligrams per liter of BOD, the Agency requests that

[[Page 23673]]

commenters provide any information they have on the costs of this 
option.
    2. The proposed rule solicited comment on a second option, Option 
2, that would allow facilities operating wells that have caused or may 
cause fluid movement to conduct hydrogeologic demonstrations to show 
that injection will not cause fluids that exceed any national primary 
drinking water regulations in 40 CFR part 141 and other health-based 
standards to enter any USDW. Option 2 would also require well owners 
and/or operators that cannot make this demonstration to provide 
additional treatment as needed to address contaminants of concern. 
Further, Option 2 requires advanced wastewater treatment and high-level 
disinfection to be in place by 2015. The Agency requests comment on 
whether the findings from the relative risk assessment, specifically 
those regarding deep well injection, suggest anything regarding the 
practicability and feasibility of this approach. Should facilities be 
granted the opportunity to conduct hydrogeologic demonstrations (and 
expend the resources and funds necessary) despite the inherent 
difficulties and uncertainties regarding the extent, location, and 
connectivity of possible natural conduits for flow identified in the 
relative risk assessment? If facilities should be granted this 
opportunity, how should the UIC director in his/her review of a 
demonstration, address the technical difficulties in determining the 
extent of the contamination, and the location of conduits for flow into 
USDWs, so that the demonstration may be deemed adequate? Given the 
uncertainty that accompanies the effort to analytically or numerically 
simulate the fate and transport of fluid and stressors in South 
Florida's deep underground environment, EPA solicits comment on ways 
that a satisfactory hydrogeological demonstration can be conducted. 
Finally, the proposed rule included a ``sunset provision'' (requiring 
advanced wastewater treatment and high-level disinfection by 2015) as 
part of this option even if protection of USDWs is being demonstrated. 
EPA requests comment on an alternative that would allow the State 
Director to authorize updated hydrogeologic assessments and defer 
treatment requirements beyond 2015 if the assessments continued to 
demonstrate adequate protection of the USDW.
    3. One option to address the fluid movement that has occurred, 
while also preventing the endangerment of USDWs, might be to promulgate 
new Class V requirements specific to deep municipal wells in South 
Florida. In a 1999 stakeholders meeting, the Agency discussed two 
options for reclassifying these wells as Class V. One of these options 
would reclassify the wells based on a determination that the wells no 
longer meet the regulatory definition of a Class I well. Another option 
would involve converting the wells to Class V by physically altering 
the wells so that they inject directly into or above formations 
containing the lowermost USDW. Two other options discussed at the 
stakeholders meeting were (1) to make no regulatory change (and enforce 
the existing requirements) and (2) to amend the Class I regulations to 
address the fluid movement issues. EPA ultimately proposed this last 
option and published proposed revisions to the Class I requirements. 
EPA stated in the preamble to the July 7, 2000, proposal (65 FR 42237): 
``The Agency is not planning to allow reclassification unless the well 
was misclassified in the first instance. Misclassification might have 
occurred if the well did not originally meet the definition of a Class 
I well. The facility could demonstrate this if new information has 
become available that proves that the well originally was injecting 
into a USDW and therefore would meet the definition of a Class V 
well.''
    EPA is now reconsidering the reclassification option. 
Reclassification could be accomplished without any regulatory changes 
to the Class I definitions or the Class I ``no fluid movement'' 
requirements. Following publication of this NODA and receipt of 
comments on this option, EPA, if it chose the reclassification option, 
would publish final revisions to the Class V regulations that include 
the same operating conditions that EPA would have promulgated as 
revisions to the Class I regulations. This option is contrasted with 
the approach discussed more fully in the July 7, 2000, proposal to keep 
the wells as Class I and add the necessary operating conditions to the 
Class I regulations. Either approach could be used to place the same 
operating conditions on continued injection activities and provide 
identical protection to USDWs.
    In addition, EPA is considering whether there might be a need to 
promulgate the operating conditions under consideration as final 
regulations under both the Class I and Class V regulatory frameworks. 
This might be necessary in order to ensure that the new requirements 
apply to all municipal waste disposal wells in South Florida that cause 
or may cause fluid movement into a USDW, regardless of whether it is 
determined that a particular well may be reclassified as Class V or 
must remain in Class I. EPA invites comment on the need for 
incorporating the proposed operating conditions into either, or both, 
the Class I and Class V regulations. EPA notes that the costs of 
installing a specified level of treatment would be the same, regardless 
of whether a particular well is classified as Class I or Class V.
    One potential advantage of the reclassification option is that it 
could correct any previous misclassification of wells in South Florida.
    A potential disadvantage of the reclassification option is that it 
could lead to reclassification requests associated with other wells in 
other parts of the country and could limit the flexibility of local 
permit writers to make classification determinations.
    In summary, with regard to reclassification of Class I wells, the 
Agency requests comment on whether the findings from the relative risk 
assessment, specifically those regarding deep well injection, suggest 
that some South Florida wells may have been misclassified as Class I 
wells? Do the findings suggest that some wells in South Florida may, in 
fact, discharge directly to (and not below) formations containing a 
USDW? Do the findings suggest that this misclassification should be 
accepted for the entire group of South Florida municipal wells, or only 
a subset? Should the regulatory requirements under consideration be 
promulgated under provisions for Class I or Class V? If 
reclassification is only appropriate for some of the covered South 
Florida wells, should the regulatory requirements under consideration 
be promulgated under provisions for both Class I and Class V.

    Dated: April 17, 2003.
G. Tracy Mehan III,
Assistant Administrator for Water.
[FR Doc. 03-10268 Filed 5-2-03; 8:45 am]
BILLING CODE 6560-50-P